Power supply package with built-in radio frequency identification tag

ABSTRACT

A method includes providing a power supply package (PSP) that includes a power supply, an RFID tag, and a power switch, where a control terminal of the power switch is coupled to an output terminal of the RFID tag, and load path terminals of the power switch are coupled between an output terminal of the PSP and a first terminal of the power supply, where a control register of the RFID tag is pre-programmed with a first value such that the RFID tag is configured to generate a first control signal that turns off the power switch; receiving, by the RFID tag, a second value for the control register of the RFID tag; and writing, by the RFID tag, the second value to the control register of the RFID tag such that the RFID tag is configured to generate a second control signal that turns on the power switch.

TECHNICAL FIELD

The present invention relates generally to radio-frequencyidentification (RFID) tags, and, in particular embodiments, to powersupply packages with built-in RFID tags for anti-theft purpose.

BACKGROUND

RFID is used to uniquely identifying items using radio waves. A typicalRFID system comprises an RFID tag and an RFID reader (also referred toas a reader, or a reader device). The RFID reader sends an interrogatingsignal (e.g., a radio-frequency signal) to the RFID tag, and the RFIDtag responds with its unique information. RFID systems may operate atvarious frequency ranges, e.g., a low frequency (LF) range between 125KHz and 134 KHz, a high frequency (HF) of 13.56 MHz, or an ultra-highfrequency range between 856 MHz and 928 MHz. Various industry standardsexist for RFID communication, e.g., ISO 15693, ISO 18000, and ISO 24730.

Near-field communication (NFC) is a subset of the RFID communication andoperates at the same frequency (e.g., 13.56 MHz) as HF RFID readers andtags. Various standards for NFC exist, such as ISO/IEC 14443, ISO/IEC18092, and ISO/IEC 21481. While RFID system may work for distances up tohundreds of meters, near-field communication typically works at a shortdistance, e.g., a few centimeters. Due to its short read range and thesecurity associated with such a short communication distance, NFCsystems have been used in applications such as contactless payment,electronic ID card, and electronic keycard.

SUMMARY

In some embodiments, a method includes providing a power supply packagethat includes a power supply, a radio-frequency identification (RFID)tag coupled to the power supply, and a power switch, where a controlterminal of the power switch is coupled to an output terminal of theRFID tag, and load path terminals of the power switch are coupledbetween an output terminal of the power supply package and a firstterminal of the power supply, where a control register of the RFID tagis pre-programmed with a first value such that the RFID tag isconfigured to generate, at the output terminal of the RFID tag, a firstcontrol signal that turns off the power switch. The method furtherincludes receiving, by the RFID tag, a second value for the controlregister of the RFID tag; and writing, by the RFID tag, the second valueto the control register of the RFID tag such that the RFID tag isconfigured to generate, at the output terminal of the RFID tag, a secondcontrol signal that turns on the power switch.

In some embodiments, a method includes receiving a power supply packagehaving a first output terminal and a second output terminal, the powersupply package comprising a power supply, a radio-frequencyidentification (RFID) tag coupled to the power supply, and a powerswitch, wherein a control terminal of the power switch is coupled to anoutput terminal of the RFID tag, and load path terminals of the powerswitch are coupled between the first output terminal and a first one ofa positive terminal and a negative terminal of the power supply, whereinthe RFID tag is pre-programmed to a first operating state, wherein inthe first operating state, the RFID tag is configured to generate, atthe output terminal of the RFID tag, a first control signal that turnsoff the power switch, wherein the power supply package is configured tobe disabled when the power switch is turned off; determining that thepower supply package needs to be enabled; and in response to determiningthat the power supply package needs to be enabled, programming the RFIDtag to a second operating state, wherein in the second operating state,the RFID tag is configured to generate, at the output terminal of theRFID tag, a second control signal that turns on the power switch.

In some embodiments, a power supply package includes a first outputterminal and a second output terminal; a power supply; a power switchcoupled between the first output terminal and a first terminal of thepower supply; and a radio-frequency identification (RFID) device coupledto the power supply and the power switch, the RFID device comprising: anRFID block configured to support RFID communication; a memory configuredto store a pulse-width modulation (PWM) parameter; and a PWM circuitconfigured to generate a PWM signal at an output of the PWM circuit,wherein a duty cycle of the PWM signal generated by the PWM circuit isdetermined by the PWM parameter, wherein the output of the PWM circuitis coupled to a control terminal of the power switch.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims. In the figures, identicalreference symbols generally designate the same component partsthroughout the various views, which will generally not be re-describedin the interest of brevity. For a more complete understanding of theinvention, reference is now made to the following descriptions taken inconjunction with the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of an RFID tag, in some embodiments;

FIG. 2 illustrates the partition of a memory module of an RFID tag, insome embodiments;

FIG. 3 illustrates a schematic view of a power supply package with abuilt-in RFID tag, in an embodiment;

FIG. 4 illustrates a schematic view of a power supply package with abuilt-in RFID tags, in another embodiment;

FIG. 5 illustrates a schematic view of a power supply package with abuilt-in RFID tag, in yet another embodiment; and

FIG. 6 illustrates a flow chart of a method for operating a power supplypackage with a built-in RFID tag, in some embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The present invention will be described with respect to exemplaryembodiments in a specific context, namely systems and methods for powersupply packages with built-in RFID tags for anti-theft purpose.

FIG. 1 illustrates a block diagram of an RFID tag 100, in someembodiments. The RFID tag 100 includes an RFID block 101, aconfiguration and control (CC) circuit 103, a memory module 105, anoscillator 107, a pulse-width modulation (PWM) circuit 109, and buffers111. For simplicity, not all features of the RFID tag 100 areillustrated in FIG. 1. The RFID tag 100 of FIG. 1 may be formed as astand-alone RFID tag, or may be formed with additional functional blocksto form an RFID device with enhanced functions.

The RFID block 101 comprises circuits that provide the capability forthe RFID tag 100 to communicate wirelessly with a reader. The RFID block101 may support one or more of the standards for RFID communicationand/or NFC communication. The RFID block 101 may also supportproprietary wireless communication protocols. As illustrated in FIG. 1,the RFID block 101 has terminals 115 for connecting to an antenna (see,e.g., 133 in FIG. 3). In some embodiments, through the RFID block 101, areader device can access (e.g., read and/or write) the memory module 105and a memory region (e.g., a register region 104) of the CC circuit 103.For example, through the RFID block 101, the reader device may writevalues to certain configuration registers (e.g., in the memory module105) to set the operational mode of the RFID tag 100, and may send datato the RFID tag 100. FIG. 1 illustrates data paths (e.g., bi-directionaldata paths, or one direction data paths) between various blocks of theRFID tag 100. The data paths may be used to transmit/receive signals forcontrol purpose and/or for data access (e.g., read/write) purpose.

The memory module 105 comprises a non-volatile memory, such as anelectrically erasable programmable read-only memory (EEPROM), in someembodiments. The memory module 105 may be partitioned into differentregions to store different types of data. An example partitioning of thememory module 105 is illustrated in FIG. 2.

In the example of FIG. 2, the memory module 105 (e.g., an EEPROM) is anon-volatile memory, and is partitioned into a first non-volatile memoryregion 123 and a second non-volatile memory region 125. The firstnon-volatile memory region 123 and the second non-volatile memory region125 are password-protected regions such that access (e.g., read/write)to these regions are granted to RFID readers that could provide acorrect password. The memory module 105 may include other storageregions that are not illustrated in FIG. 2. The other storage regionsmay include memory regions that are not password protected (e.g., couldbe accessed by an RFID reader without using a password). In someembodiments, the memory module 105 has another memory region for storingdata that are sent to the PWM circuit 109 (e.g., through the CC circuit103) during operation of the RFID tag 100 in certain operation mode.

In the example of FIG. 2, the first non-volatile memory region 123comprises one or more PWM registers 124 (also referred to as controlregisters, or PWM control registers), which one or more PWM registers124 store PWM parameter values that are used to determine variousaspects of the operation of the RFID tag 100. For example, one of thePWM registers 124 may store a value that determines the duty cycle of aPWM signal generated by the PWM circuit 109. The second non-volatilememory region 125 may store a password that is used for deviceauthentication and/or protection (e.g., read/write access control). Moredetails are discussed hereinafter. The partition illustrated in FIG. 2is merely an example, other partitions of the memory module 105 arepossible and are fully intended to be included within the scope of thepresent disclosure.

Referring back to FIG. 1, the RFID tag 100 includes the CC circuit 103.In the illustrated embodiment, the CC circuit 103 has a register region104. The register region 104 may be used to store data that arepass-through to the PWM circuit 109 in certain operation mode. The CCcircuit 103 comprises a state machine, in some embodiments. The statemachine includes circuits configured to perform a sequence ofpre-determined operations depending on a sequence of events presented tothe state machine, in some embodiments. In accordance with someembodiments, the state machine of CC circuit 103 controls the operationof the RFID tag 100 based on the settings (e.g., PWM parameter values)of the RFID tag 100, and no micro-controller (MCU) is used (e.g.,formed) in the RFID tag 100. Note that an MCU here refers to a smallcomputer on a single integrated circuit, and may include one or morecentral processing units (CPUs) along with integrated memory andinput/output (IO) peripherals. By using a state machine instead of anMCU for controlling the operation of the RFID tag 100, cost of the RFIDtag 100 is greatly reduced.

The PWM circuit 109 includes circuits for generating PWM waveforms(e.g., comprising “zero” and “one” logic levels) with specifiedfrequencies and duty cycles, based on the PWM settings (e.g., PWMparameters) stored in the first non-volatile memory region 123. The PWMwaveform may also be referred to as a PWM signal. In some embodiments,the PWM circuit 109 generates one or more PWM signals simultaneously,and outputs the generated PWM signals at the output channels 110 (alsoreferred to as output ports, or outputs) of the PWM circuit. In someembodiments where more than one PWM signals are generated simultaneouslyby the PWM circuit 109, the more than one PWM signals are independentfrom each other, and are generated based on different PWM parametersstored in, e.g., the PWM registers 124 in the first non-volatile memoryregion 123.

In an embodiment, a PWM parameter includes a PWM channel ID and a PWMtone value, where the PWM tone value further includes a PWM enablesignal, a PWM frequency, and a PWM pulse width. The PWM channel IDindicates which one of the output channels 110 of the PWM circuit 109 isthe PWM parameter intended for (e.g., controlled by the PWM parameter).The PWM enable signal indicates the state (e.g., ON or OFF) of the PWMchannel specified by the PWM channel ID. When the PWM enable signal isON, the corresponding output channel is enabled and outputs a PWMsignal; when the PWM enable signal is OFF, the corresponding outputchannel is turned off (e.g., no PWM signal is generated). The PWMfrequency indicates the frequency of the PWM signal to be generated atthe output channel indicated by the PWM channel ID. In some embodiments,the PWM signal is generated by the PWM circuit 109 using a digitalwaveform, e.g., a waveform derived from an output of the oscillator 107.The PWM pulse width and the PWM frequency indicate the duty cycle of thePWM waveform, in some embodiments. For example, the duty cycle of thePWM waveform may be determined by dividing the pulse width (e.g.,indicated by the PWM pulse width) of the PWM waveform by the period ofthe PWM waveform, which is inversely proportional to the frequency ofthe PWM waveform. In some embodiments, the PWM circuit 109, based on thePWM parameter received, generates a PWM waveform with a frequencyspecified by the PWM frequency and a duty cycle specified by the PWMpulse width and the PWM frequency, at an output channel specified by thePWM channel ID, when the output channel is enabled (e.g., PWM enablesignal is ON).

Still referring to FIG. 1, the oscillator 107 provides a clock signal todrive the circuits of the RFID tag 100, and is used as a reference fortiming. Any suitable oscillator may be used, and thus, details are notrepeated here. FIG. 1 further illustrates one or more buffers 111coupled between output ports 110 of the PWM circuit 109 and respectiveoutput terminals 113 of the RFID tag 100. The buffers 111 may be anysuitable buffers (e.g., transistors, open-collector drives), and may beused to shift voltages of the PWM waveforms from the internal powerdomain (e.g., voltage levels within the RFID tag 100) to the externalpower domain (e.g., voltage levels outside the RFID tag 100). In someembodiments, the buffer in is formed using NMOS and PMOS techniques, andmay have multiple NMOS/PMOS stages in parallel in order to adjust theoutput current to, e.g., provide improved driving capability at theoutput terminals 113. In the illustrated embodiment, the outputs of thebuffers 111 are digital signal (e.g., PWM waveforms buffered by thebuffers 111), and are sent to the output terminals 113. The outputterminal 113 is coupled to a control terminal (e.g., a gate) of a powerswitch 139 (e.g., a transistor), and are used to turn ON or OFF thepower switch, in the example of FIG. 3. Therefore, the PWM signals mayalso be referred to as control signals. In addition, FIG. 1 illustratesa power supply terminal 117 (e.g., a voltage supply terminal Vdd) and areference voltage terminal 118 (e.g., electrical ground terminal GND)for the RFID tag 100.

FIG. 3 illustrates a schematic view of a power supply package 200 with abuilt-in RFID tag, in an embodiment. The power supply package 200includes a power supply 135, an RFID tag 100, a voltage regulator 137, apower switch 139, a resistor 145, and an antenna 133. The power supply135 may be a battery with a voltage between, e.g., 5V and 24 V, and maybe a rechargeable battery for devices such as a mobile device, aconsumer electronics equipment, a power tool, or the similar, as anexample. The power supply 135 may be a switched-mode power supply(SMPS), as another example. In the discussion below, battery is used anexample of the power supply 135, and therefore, the power supply 135 maybe referred to as a battery 135, and the power supply package 200 may bereferred to as a battery pack 200. Although battery is used as anexample of the power supply 135, the power supply 135 may be anysuitable type of power supply, such as a SMPS. In an embodiment, thepower switch 139 is a transistor, such as a metal-oxide-semiconductorfield-effect transistor (MOSFET), and the control terminal is the gateof the transistor. Besides MOSFET, other types of power switches, suchas bipolar junction transistors (BJTs), gallium nitride (GaN)transistors, or the like, may also be used as the power switch 139. Inthe discussion herein, the two terminals of the power switch 139 otherthan the control terminal are referred to as the load path terminals.For example, the source/drain terminals of a MOSFET are referred to asthe load path terminals of the MOSFET.

Traditional power supply packages (e.g., power supply packages withoutthe built-in RFID tag 100 and the power switch 139) may not havebuilt-in features to deter theft in a retail environment. As ananti-theft measure, traditional power supply packages are usuallypackaged side-by-side with an anti-theft device (e.g., a magnetic strip)in a, e.g., plastic package. However, if the plastic package is cut openand the transitional power supply package removed from the plasticpackage, the traditional power supply package itself offers noprotection or deterrence against theft. In contrast, the presentlydisclosed power supply packages (e.g., 200, 200A, 200B) provide built-inanti-theft features by integrating the RFID tag 100 and the power switch139 within the power supply packages (e.g., within the external housingof the power supply package). For example, the output of the powersupply package 200 is pre-programmed to be disabled, e.g., at amanufacturing facility of the power supply package. Subsequently, afterit is determined that the power supply package 200 needs to be enabled(e.g., after payment is confirmed at a point of sale such as a retailstore, or after receiving authorization to enable the power supplypackage 200), the output of the power supply package 200 is enabled,e.g., by the store clerk. Therefore, a stolen power supply package 200is inoperable, since the output of the power supply package 200 isdisabled. Details of the disclosed power supply packages are discussedbelow.

In FIG. 3, the voltage regulator 137 is coupled between the battery 135and the RFID tag 100. The voltage regulator 137 converts (e.g.,down-converts) the voltage provided by the battery 135 to a voltagesuitable for the RFID tag 100. For example, the battery 135 may providea voltage Vb of 24V, and the voltage regulator 137 down-converts thevoltage Vb to 3V and provides the down-converted voltage to the voltagesupply terminal Vdd of the RFID tag 100. As illustrated in FIG. 3, thepositive terminal and the negative terminal of the battery 135 arecoupled to a first input and a second input of the voltage regulator137, and the output of the voltage regulator 137 is coupled to thevoltage supply terminal Vdd. The reference voltage terminal (e.g., theGND terminal) of the RFID tag 100 is coupled to the negative terminal ofthe battery 135. The output from the voltage regulator 137 is used todrive the digital circuits (e.g., the CC circuit 103, the PWM circuit109, the oscillator 107 and the buffer 111) of the RFID tag 100. Notethat the RF portion of the RFID tag 100, such as the RFID block 101 andits access to (e.g., read/write) of the memory module 105, could operateusing the energy from the RFID reader 131 through electromagneticcoupling, and therefore, could operate without the battery 135.

In FIG. 3, the power supply package 200 has two output terminals 141 and143. The output terminal 141 is coupled to the positive terminal of thebattery 135, and the output terminal 143 is coupled to a first load pathterminal (e.g., a source/drain terminal) of the power switch 139 (e.g.,a MOSFET). A second load path terminal of the power switch 139 iscoupled to a reference voltage node 147, which is connected to, e.g.,the electrical ground and has a same voltage as the negative terminal ofthe battery 135. The control terminal (e.g., a gate) of the power switch139 is coupled to the output terminal 113 of the RFID tag 100. FIG. 3further illustrates a resistor 145 coupled between the control terminalof the power switch 139 and the reference voltage node (e.g., electricalground).

As illustrated in FIG. 3, the terminals 115 of the RFID tag 100 areconnected to an antenna 133. In addition, FIG. 3 illustrates an RFIDreader 131, such as an RFID-enabled (or NFC-enabled) smart phone, thatis used to interact wirelessly with the RFID tag 100 for reading orwriting data in, e.g., the memory module 105. Note that althoughillustrated in FIG. 3, the RFID reader 131 is not part of the powersupply package 200.

As discussed above, the first non-volatile memory region 123 (see FIG.2) includes one or more PWM registers 124, each of which is used tostore a PWM parameter. The PWM parameter may include values thatindicate the channel ID, the PWM signal frequency, and the duty cycle ofthe PWM signal generated for the identified channel. In an embodiment,the value of a PWM register 124 in the first non-volatile memory region123 is set (e.g., pre-programmed) to a value that indicates a 0% dutycycle, e.g., when the power supply package 200 is manufactured at amanufacturing facility. The channel ID of the PWM parameter stored inthe PWM register 124 points to an output channel of the PWM circuit 109that is coupled to the output terminal 113 in FIG. 3 (e.g., the outputterminal 113 connected to the power switch 139). The PWM frequency ofthe PWM parameter may be set to any PWM frequency value supported by thePWM circuit 109. Since in the present disclosure, the duty cycle of thePWM signal is set to either a 0% duty cycle or a 100% duty cycle, thePWM signal generated is actually a direct current (DC) signal with alogic low or logic high value, thus the PWM frequency may be set to anysupported value.

In addition, a password is stored in the second non-volatile memoryregion 125, e.g., at the manufacturing facility of the power supplypackage 200. The password may be a unique message digest produced by ahashing process. For example, the password may be formed byconcatenating a batch ID with a device ID to form a digital sequence,then processing the digital sequence with a hashing process to producethe password (e.g., a 64-bit password). The batch ID may be aconfidential ID number assigned to a particular manufacturing facilityor a plurality of manufacturing facilities in a specific geographicregion. The device ID is a unique ID (e.g., a chip ID) assigned to eachRFID tag 100 manufactured and stored in the RFID tag 100, and may beread out by an RFID reader. Other ways to produce the password arepossible, and are fully intended to be included within the scope of thepresent disclosure.

The password stored in the second non-volatile memory region 125 may beused to control access (e.g., writing and/or reading) topassword-protected regions of the memory module 105. In the illustratedembodiment, when the RFID reader 131 reads from or writes to thepassword-protected region (e.g., the PWM register 124) in the memorymodule 105, the RFID reader 131 needs to send a password to the RFID tag100 first. The RFID tag 100 compares the received password with thepassword stored in the second non-volatile memory region 125. Access tothe password-protected regions of the memory module 105 is granted onlywhen the received password matches the password stored.

As discussed above, the PWM parameter stored in the PWM register 124(see FIG. 2) indicates a 0% duty cycle by default (e.g., out of amanufacturing facility). Therefore, when the battery 135 provides avoltage, e.g., after the (re-chargeable) battery 135 is charged, the PWMcircuit 109 of the RFID tag 100 generates a PWM signal with 0% dutycycle at the output terminal 113, which PWM signal is a logic lowsignal, and the power switch 139 is turned off. As a result, the outputterminal 143 of the power supply package 200 is disconnected from thereference voltage node 147 (e.g., electrical ground), and iselectrically floating (e.g., disconnected from the rest of the circuitin the power supply package 200). Therefore, the output of the powersupply package 200 is disabled. In other words, if a load is connectedbetween the output terminals 141 and 143, no electrical current willflow through the load. The resistor 145 functions as a pull-downresistor to ensure that the gate of the power switch 139 is groundedwhen the output terminal 113 is not driving the power switch 139. Aresistance of the resistor 145 may be 100KΩ, as an example. In someembodiments, the resistor 145 is omitted.

After it is determined that the power supply package 200 needs to beenabled, for example, at a point of sale (e.g., a retail store, or awarehouse for an on-line shopping website) after payment of the powersupply package 200 is confirmed, the power supply package 200 is enabledby changing the duty cycle of the PWM signal to 100%. For example, thestore clerk may use the RFID reader 131 to write a new value to the PWMregister 124, such that the duty cycle indicated by the PWM parameterstored in the PWM register 124 indicates a 100% duty cycle. When thebattery 135 provides a voltage, e.g., after the (re-chargeable) battery135 is charged, the PWM circuit 109 of the RFID tag 100 generates a PWMsignal with a 100% duty cycle at the output terminal 113, which PWMsignal is a logic high signal, and the power switch 139 is turned on. Asa result, the output terminal 143 of the power supply package 200 iscoupled to the reference voltage node 147 (e.g., electrical ground).Therefore, the output of the power supply package 200 is enabled. Inother words, if a load is connected between the output terminals 141 and143, an electrical current will flow through the load.

To access (e.g., read/write) the password-protected regions of thememory module 105, the RFID reader 131 needs to send a locally generatedpassword to the RFID tag 100 that matches the stored password in thememory module 105. To obtain the locally generated password, the storeclerk (or a computer program) may obtain the batch ID from a secureserver, then concatenate the batch ID with the device ID (which may beread out from the RFID tag without using a password) to form a digitalsequence, and process the digital sequence with a hashing process togenerate the password.

In addition, the memory module 105 may store a digital signature (e.g.,a 128-bit binary sequence) that is used to verify that the power supplypackage 200 is an authentic (e.g., branded) product instead of acounterfeit. While the PWM parameter(s) and the password of the RFID tagare stored in password-protected regions of the memory module 105, thedigital signature is stored in a non-protected region such that an RFIDreader can read the stored digital signature without a password, in someembodiments. To verify the authenticity of the power supply package 200,an authentication process may be performed. In an example authenticationprocess, the digital signature stored in the memory module 105 is readout by an RFID reader, then decrypted by a public key verificationprocess such as an ecliptic curve digital signature algorithm (ECDSA)using a public key, which pubic key may be publicly available from themanufacturer. The ECDSA produces a decryption output (e.g., a digitalsequence), which is compared with, e.g., a serial number (also referredto as a battery ID) of the power supply package 200, which serial numbermay be printed on the packaging and/or the exterior housing of the powersupply package 200. A matching between the decryption output and theserial number may indicate the authenticity of the power supply package200, and a mismatch may indicate a counterfeit, as an example. Themanufacturer may or may not use the device ID of the RFID tag 100 as theserial number of the power supply package 200.

Note that the example here assumes that power switch 139 is turned offby a logic low voltage applied at the gate of the power switch and isturned on by a logic high voltage at the gate. Devices such as N-typetransistor may have such properties. However, other types of devices,such as P-type transistors, may have opposite polarities for the controlvoltage (e.g., the voltage applied at the gate of the transistors) toturn on or off the transistors. One skilled in the art will readilyappreciates that the duty cycle may be set to 100% to disable the powersupply package and set to 0% to enable the power supply package, if thepolarity of the control voltage for the power switch 139 is inverted.

FIG. 4 illustrates a schematic view of a power supply package 200A witha built-in RFID tags, in another embodiment. The power supply package200A is similar to the power supply package 200, but with an additionalpower switch. In particular, a power switch 139A is coupled between theoutput terminal 141 and the positive terminal of the battery 135, and apower switch 139B is coupled between the output terminal 143 and thereference voltage node 147 (e.g., electrical ground). The power switch139A and 139B may be the same as the power switch 139 in FIG. 3. In theexample of FIG. 4, the PWM circuit 109 of the RFID tag 100 generates twoPWM signals at two output terminals 113, where each of the PWM signal iscoupled to the control terminal of a respective power switch (e.g., 139Aor 139B). Two PWM registers 124 may be used to store two different PWMparameters for controlling the two output channels of the PWM circuit109. Similar to the power supply package 200, the PWM parameters thatcontrols the PWM circuit may be pre-programmed with a duty cycle of 0%(e.g., at a manufacturing facility) to disable the output of the powersupply package 200A. When the power supply package 200A is disabled,both output terminals 141 and 143 are disconnected (e.g., electricallyfloating) from the rest of the circuit of the power supply package 200A.At the point of sale, the PWM parameters may be set (e.g., programmed)with a duty cycle of 100% to enable the output of the power supplypackage 200A, after payment is confirmed.

In some embodiments, as an added layer of security, two differentpasswords are stored in the second non-volatile memory region 125, e.g.,at the manufacturing facility, and the power supply package 200A aredisabled. To enable the power supply package 200A, two passwords aregenerated locally and used for writing new values (e.g., indicating 100%duty cycle) to the two PWM registers. A matching between a first locallygenerated password and a first stored password will allow writing to afirst PWM register, and a matching between a second locally generatedpassword and a second stored password will allow writing to a second PWMregister. Therefore, if one of the locally generated passwords does notmatch the respective stored password in the memory module 105, one ofthe power switches 139A/139B remains turned off, thus still rending thepower supply package 200A inoperable.

As illustrated in FIG. 4, each power switch has a pull-down resistor(e.g., 145A or 145B). In another embodiment, only one pull-down resistor(e.g., 145A or 145B) is used and is shared by both power switches 139Aand 139B, similar to the example in FIG. 5.

In yet another embodiment, the power switch 139B and the resistor 145Bin FIG. 4 are removed, and the output terminal 143 is directly connectedto the reference voltage node 147. With such an implementation, theoutput terminal 141 is disconnected from the rest of the circuit of thepower supply package when the power supply package is disabled.

FIG. 5 illustrates a schematic view of a power supply package 200B witha built-in RFID tag, in yet another embodiment. The power supply package200B is similar to the power supply package 200, but with an additionalpower switch (e.g., 139A) coupled between the output terminal 141 andthe positive terminal of the battery 135. The power switch 139A and 139Bin FIG. 5 may be the same as the power switch 139 in FIG. 3. In theexample of FIG. 5, the same PWM signal generated by the PWM circuit 109is coupled to the control terminals of both power switches 139A and139B. Operation of the power supply package 200B is similar to thosediscussed above, as one skilled in the art will readily appreciate, thusdetails are not repeated.

FIG. 6 illustrates a flow chart of a method 1000 for operating a powersupply package with a built-in RFID tag, in some embodiments. It shouldbe understood that the embodiment method shown in FIG. 6 is merely anexample of many possible embodiment methods. One of ordinary skill inthe art would recognize many variations, alternatives, andmodifications. For example, various steps as illustrated in FIG. 6 maybe added, removed, replaced, rearranged and repeated.

Referring to FIG. 6, at step 1010, a power supply package is providedwhich comprises a power supply, a radio-frequency identification (RFID)tag coupled to the power supply, and a power switch, wherein a controlterminal of the power switch is coupled to an output terminal of theRFID tag, and load path terminals of the power switch are coupledbetween an output terminal of the power supply package and a firstterminal of the power supply, wherein a control register of the RFID tagis pre-programmed with a first value such that the RFID tag isconfigured to generate, at the output terminal of the RFID, a firstcontrol signal that turns off the power switch. At step 1020, a secondvalue for the control register of the RFID tag is received by the RFIDtag. At step 1030, the second value is written by the RFID tag to thecontrol register of the RFID tag such that the RFID tag is configured togenerate, at the output terminal of the RFID tag, a second controlsignal that turns on the power switch.

Embodiments may achieve advantages. For example, the disclosed powersupply packages provide effective features to deter theft. The RFID tag100 and the power switch (e.g., 139) are integrated (e.g., formedtogether) with the battery 135 to provide a low-cost anti-theftsolution. Various embodiments allow for flexibility in choosingdifferent levels of security and different levels of cost (e.g., cost ofadditional power switch).

Example embodiments of the present invention are summarized here. Otherembodiments can also be understood from the entirety of thespecification and the claims filed herein.

Example 1. In an embodiment, a method includes providing a power supplypackage comprising a power supply, a radio-frequency identification(RFID) tag coupled to the power supply, and a power switch, wherein acontrol terminal of the power switch is coupled to an output terminal ofthe RFID tag, and load path terminals of the power switch are coupledbetween an output terminal of the power supply package and a firstterminal of the power supply, wherein a control register of the RFID tagis pre-programmed with a first value such that the RFID tag isconfigured to generate, at the output terminal of the RFID tag, a firstcontrol signal that turns off the power switch; receiving, by the RFIDtag, a second value for the control register of the RFID tag; andwriting, by the RFID tag, the second value to the control register ofthe RFID tag such that the RFID tag is configured to generate, at theoutput terminal of the RFID tag, a second control signal that turns onthe power switch.

Example 2. The method of Example 1, wherein the first control signal isa first pulse-width modulation (PWM) signal generated by a PWM circuitof the RFID tag, wherein a first duty cycle of the first PWM signal isdetermined by the first value in the control register.

Example 3. The method of Example 2, wherein the second control signal isa second PWM signal generated by the PWM circuit, wherein a second dutycycle of the second PWM signal is determined by the second value in thecontrol register.

Example 4. The method of Example 3, wherein the first duty cycle is 0%,and the second duty cycle is 100%.

Example 5. The method of Example 3, wherein the first duty cycle is100%, and the second duty cycle is 0%.

Example 6. The method of Example 1, wherein writing the second value tothe control register comprises: receiving, by the RFID tag, a firstpassword from an RFID reader; verifying, by the RFID tag, that the firstpassword matches a second password stored in the RFID tag; and afterverifying that the first password matches the second password, writing,through an RFID block of the RFID tag, the second value to the controlregister.

Example 7. The method of Example 1, wherein the power supply is abattery or a switched-mode power supply (SMPS).

Example 8. The method of Example 1, wherein the power switch is atransistor, and the control terminal of the power switch is a gate ofthe transistor.

Example 9. The method of Example 1, wherein the first terminal of thepower supply is a positive terminal of the power supply.

Example 10. The method of Example 1, wherein the first terminal of thepower supply is a negative terminal of the power supply.

Example 11. In an embodiment, a method includes receiving a power supplypackage having a first output terminal and a second output terminal, thepower supply package comprising a power supply, a radio-frequencyidentification (RFID) tag coupled to the power supply, and a powerswitch, wherein a control terminal of the power switch is coupled to anoutput terminal of the RFID tag, and load path terminals of the powerswitch are coupled between the first output terminal and a first one ofa positive terminal and a negative terminal of the power supply, whereinthe RFID tag is pre-programmed to a first operating state, wherein inthe first operating state, the RFID tag is configured to generate, atthe output terminal of the RFID tag, a first control signal that turnsoff the power switch, wherein the power supply package is configured tobe disabled when the power switch is turned off; determining that thepower supply package needs to be enabled; and in response to determiningthat the power supply package needs to be enabled, programming the RFIDtag to a second operating state, wherein in the second operating state,the RFID tag is configured to generate, at the output terminal of theRFID tag, a second control signal that turns on the power switch.

Example 12. The method of Example 11, wherein the first output terminalis electrically floating when the power switch is turned off, whereinthe first output terminal has a same voltage as the positive terminal orthe negative terminal of the power supply when the power switch isturned on.

Example 13. The method of Example 11, wherein RFID tag comprises apulse-width modulation (PWM) circuit that is configured to generate aPWM signal at the output terminal of the RFID tag, wherein a duty cycleof the PWM signal is controlled by a control register of the RFID tag,wherein the control register is pre-programmed with a first value thatindicates a first duty cycle for the PWM signal.

Example 14. The method of Example 13, wherein programming the RFID tagcomprises writing a second value to the control register, wherein thesecond value indicates a second duty cycle different from the first dutycycle.

Example 15. The method of Example 14, wherein the first duty cycle is0%, and the second duty cycle is 100%.

Example 16. The method of Example 14, wherein the first duty cycle is100%, and the second duty cycle is 0%.

Example 17. In an embodiment, a power supply package includes a firstoutput terminal and a second output terminal; a power supply; a powerswitch coupled between the first output terminal and a first terminal ofthe power supply; and a radio-frequency identification (RFID) devicecoupled to the power supply and the power switch, the RFID devicecomprising: an RFID block configured to support RFID communication; amemory configured to store a pulse-width modulation (PWM) parameter; anda PWM circuit configured to generate a PWM signal at an output of thePWM circuit, wherein a duty cycle of the PWM signal generated by the PWMcircuit is determined by the PWM parameter, wherein the output of thePWM circuit is coupled to a control terminal of the power switch.

Example 18. The power supply package of Example 17, wherein the powersupply is a battery.

Example 19. The power supply package of Example 17, wherein the powersupply is a switched-mode power supply (SMPS).

Example 20. The power supply package of Example 17, wherein the firstterminal of the power supply is a positive terminal of the power supply.

Example 21. The power supply package of Example 17, wherein the firstterminal of the power supply is a negative terminal of the power supply.

Example 22. The power supply package of Example 17, wherein the PWMparameter indicates a duty cycle of 0% or a duty cycle of 100% for thePWM signal generated by the PWM circuit.

Example 23. The power supply package of Example 22, wherein the PWMparameter is pre-programmed to a first value indicating a first dutycycle for the PWM signal, wherein the PWM parameter is configured to beset to a second value different from the first value subsequently, thesecond value indicating a second duty cycle for the PWM signal.

Example 24. The power supply package of Example 23, wherein the firstduty cycle is 0%, and the second duty cycle is 100%.

Example 25. The power supply package of Example 23, wherein the firstduty cycle is 100%, and the second duty cycle is 0%.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A method comprising: providing a power supply package comprising a power supply, a radio-frequency identification (RFID) tag coupled to the power supply, and a power switch, wherein a control terminal of the power switch is coupled to an output terminal of the RFID tag, a first load path terminal of the power switch is coupled to an output terminal of the power supply package, and a second load path terminal of the power switch is coupled to and has a same voltage as a first terminal of the power supply, wherein a control register of the RFID tag is pre-programmed with a first value such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a first control signal that turns off the power switch; receiving, by the RFID tag, a second value for the control register of the RFID tag transmitted by an RFID reader; and writing, by the RFID tag, the second value to the control register of the RFID tag such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a second control signal that turns on the power switch.
 2. The method of claim 1, wherein the first control signal is a first pulse-width modulation (PWM) signal generated by a PWM circuit of the RFID tag, wherein a first duty cycle of the first PWM signal is determined by the first value in the control register.
 3. The method of claim 2, wherein the second control signal is a second PWM signal generated by the PWM circuit, wherein a second duty cycle of the second PWM signal is determined by the second value in the control register.
 4. The method of claim 3, wherein the first duty cycle is 0%, and the second duty cycle is 100%.
 5. The method of claim 3, wherein the first duty cycle is 100%, and the second duty cycle is 0%.
 6. The method of claim 1, wherein writing the second value to the control register comprises: receiving, by the RFID tag, a first password from the RFID reader; verifying, by the RFID tag, that the first password matches a second password stored in the RFID tag; and after verifying that the first password matches the second password, writing, through an RFID block of the RFID tag, the second value to the control register.
 7. The method of claim 1, wherein the power supply is a battery or a switched-mode power supply (SMPS).
 8. The method of claim 1, wherein the power switch is a transistor, and the control terminal of the power switch is a gate of the transistor.
 9. The method of claim 1, wherein the first terminal of the power supply is a positive terminal of the power supply.
 10. The method of claim 1, wherein the first terminal of the power supply is a negative terminal of the power supply.
 11. A method comprising: receiving a power supply package having a first output terminal and a second output terminal, the power supply package comprising a power supply, a radio-frequency identification (RFID) tag coupled to the power supply, and a power switch, wherein a control terminal of the power switch is coupled to an output terminal of the RFID tag, wherein a first load path terminal of the power switch is coupled to the first output terminal, and a second load path terminal of the power switch is coupled to and has a same voltage as a positive terminal of the power supply or a negative terminal of the power supply, wherein a control register of the RFID tag is pre-programmed with a first value such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a first control signal that turns off the power switch; receiving, by the RFID tag, a second value for the control register of the RFID tag from an RFID reader; and writing, by the RFID tag, the second value to the control register of the RFID tag such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a second control signal that turns on the power switch.
 12. The method of claim 11, wherein writing, by the RFID tag, the second value comprises: receiving, by the RFID tag, a first password; comparing, by the RFID tag, the first password with a second password stored in a memory region of the RFID tag; and in response to determining that the first password matches the second password, writing, by the RFID tag, the second value to the control register of the RFID tag.
 13. The method of claim 11, wherein RFID tag comprises a pulse-width modulation (PWM) circuit that is configured to generate a PWM signal at the output terminal of the RFID tag, wherein the first value of the control register of the RFID tag corresponds to a first duty cycle of the PWM signal, and the second value of the control register of the RFID tag corresponds to a second duty cycle of the PWM signal.
 14. The method of claim 13, wherein the first duty cycle is 0%, and the second duty cycle is 100%.
 15. The method of claim 14, wherein the power switch is a N-type transistor, and the control terminal of the power switch is a gate of the N-type transistor.
 16. The method of claim 13, wherein the first duty cycle is 100%, and the second duty cycle is 0%.
 17. The method of claim 16, wherein the power switch is a P-type transistor, and the control terminal of the power switch is a gate of the P-type transistor.
 18. The method of claim 11, wherein the power supply is a battery or a switched-mode power supply (SMPS).
 19. The method of claim 11, wherein the first output terminal is electrically floating when the power switch is turned off, wherein the first output terminal has a same voltage as the positive terminal or the negative terminal of the power supply when the power switch is turned on.
 20. A method comprising: receiving a power supply package, wherein the power supply package comprises a power supply, a radio-frequency identification (RFID) tag coupled to the power supply, and a power switch, wherein a control terminal of the power switch is coupled to an output terminal of the RFID tag, wherein a first load path terminal of the power switch is coupled to an output terminal of the power supply package, and a second load path terminal of the power switch is coupled to and has a same voltage as a first terminal of the power supply, wherein a control register of the RFID tag is pre-programmed with a first value such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a first pulse-width modulation (PWM) signal that turns off the power switch; receiving, by the RFID tag, a second value for the control register of the RFID tag from an RFID reader; and writing, by the RFID tag, the second value to the control register of the RFID tag such that the RFID tag is configured to generate, at the output terminal of the RFID tag, a second PWM signal that turns on the power switch.
 21. The method of claim 20, wherein the first PWM signal has a first duty cycle, and the second PWM signal has a second duty cycle different from the first duty cycle.
 22. The method of claim 21, wherein the first duty cycle is 0% and the second duty cycle is 100%.
 23. The method of claim 21, wherein the first duty cycle is 100% and the second duty cycle is 0%. 